V6i-2 cut IMeshPipelineDevice at the measured surface and proved the mesh
pipeline could be CONSTRUCTED without naming a backend. It said plainly what it
did not claim: "the mesh pipeline does not RUN on Vulkan. Its upload bodies are
still raw GL — GlobalMeshBuffer, the VAO/IBO construction, the layer transfers."
This moves them, and gives the interface its second implementation.
GlobalMeshBuffer takes GL?. The two backing stores were already IGpuBuffer
(V4b); what still needed a context was the vertex array and the attribute
pointers, which have no RHI verb because Vulkan bakes vertex input into the
pipeline. So a backend with none builds the stores and nothing else, publishes
0 for VAO/VBO/IBO, and publishes VertexStore/IndexStore — the same buffers,
named the way a pass encoder binds them. HasStores is the backend-neutral form
of the VAO != 0 readiness test the raw-GL draw paths make. Two bodies fork on
the context and nothing else does: InitBuffers skips the vertex array, and
CommitMigration skips the rebind — on the encoder arm the field swap IS the
atomic publication, because the next pass reads whatever the field then holds.
The store deletion likewise splits: GL keeps its immediate DeleteRetired,
because the arena's own flight gate has already proven no submitted frame can
reference the store, while the other arm has no second deferral to skip and
Dispose is its retirement-queued release.
ObjectMeshManager's RequireGl narrowed to the LEGACY per-mesh upload. Its three
call sites were one modern-path constructor argument and two bodies whose every
GL statement sits inside `if (!_useModernRendering)`. The constructor now hands
the arena the nullable context; the two bodies resolve one lazily inside the
legacy branch. That branch is unreachable in every shipping configuration —
missing bindless or draw-parameters throws at startup under the N.5 ship
amendment — so the accessor survives as the guard on dead code rather than as a
blocker, and it is deleted with that code.
VulkanMeshPipelineDevice is the second implementation, and it is four
properties and two no-ops. Two things about it are worth stating rather than
leaving to be inferred. HasBindless and HasOpenGL43 answer TRUE: their names are
GL-shaped because the seam was cut from a GL device, but what they gate is the
MODERN path — one shared arena, table texture indexing, multi-draw indirect —
which Vulkan supplies unconditionally and the capability gate rejects a device
for lacking, so answering false would disable the only path that exists.
HasPendingWork answers false because the GL device's queue exists to defer work
onto the thread holding the context, and Vulkan resource work is recorded into
the frame's command buffer or routed through the retirement queue.
WbMeshAdapter selects between them once, in the one place the mesh pipeline
still names a backend. The GL arm is unchanged, including the queue-drain
guarantee its construction rollback asserts.
So composition builds the mesh pipeline on BOTH arms, and NullWbMeshAdapter is
deleted — it existed for exactly the gap this closes, and the landblock spawn
ledger now registers against the real adapter. Streaming's publication into GPU
state stops being a no-op there: the Vulkan run below builds real render data,
including the [up-null] zero-vertex caching path.
Gates. Release build green. App tests 4,112 passed / 3 skipped, against a 4,109
baseline plus the three added here. Strict GL offline pixel gate against
579e0b7f: 4.44e-05 (25 differing pixels of 563,200), inside the documented 9-31
px control band and 22x under the 0.001 threshold. One offline Vulkan run with
VK_LAYER_KHRONOS_validation proven inserted by the loader (VK_LOADER_DEBUG=layer
reports `Insert instance layer "VK_LAYER_KHRONOS_validation"`): zero validation
errors, zero warnings, a captured frame, and no [shutdown] diagnostic on either
stream.
What this does NOT claim: nothing draws the world on Vulkan yet. The three
world renderers' submission arms, the two pass executors, and the pass-structure
merge are the next commit's.
No divergence-register row: no retail-facing behaviour changes.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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